Enhanced K+/π+ Ratio from Central Collisions Between Heavy Nuclei at 1 GeV/Nucleon

We generalized the previous relativistic Vlasov-Uehling-Uhlenbeck model to be able to identify the isospin degree of freedom of particles and used it to simulate the particle production in Au + Au collisions at 1 GeV/nucleon. The momentum spectra of proton, π⁺ and K⁺ particles, the multiplicities of π⁺ and K⁺, and the K⁺/π⁺ ratio as functions of the number of participating nucleons are studied. The theoretical results agree very well with experimental data. We also analyzed the physical origin of the significant rising of K⁺/π⁺ ratio when peripheral collision goes to central collision.     

John圆的可分解性质和拟圆的一个充要条件

证明D-R2是John圆当且仅当D具有John可分解性质;D-R2是拟圆当且仅当对于任意的z1,z2∈D,存在常数c≥1,使得1cλD(z1,z2)≤λD*(z1,z2)≤cλD(z1,z2).     

Sulfonyl Imidazoles as Reagents for the Preparation of Sulfonates and Sulfonamides

Several new sulfonates and sulfonamides were synthesized with sulfonyl imidazoles as reagents. These compounds were characterized by ^1H NMR. The melting points of all solids synthesized were obtained on Fisher-Johns Melting Point Apparatus.     

STABILITY OF TWO-COMPONENT BENARD FLUID WITH SURFACE ADSORPTION ACCUMULATION

A linear stability analysis for a two-component Benard liquid with surface adsorption has revealed a dual role for the surface tension arising from the surfactant-it plays a stabilizing role in some cases and a destabilizing role in others.We have introduced a dimensionless parameter-surface excess number,proportional to the concentration gradient of solute and inversely proportional to the surface adsorption accumulation,to describe the dual effects of surface tension.We predict the existance of a critical surface excess number and calculate its value for two different boundary conditions.Our results have solved the seeming1y contrary results obtahed by Berg and Palmer and Velarde.     

中性微乳液介质增敏鲁米诺电化学发光研究

磷酸盐缓冲的中性溴化十六烷基三甲基铵-正戊醇-正庚烷微乳液介质体系对鲁米诺的电化学发光有显著的增敏作用,本文对此增敏作用进行了研究,并在此介质体系中采用电化学发光淬灭法测定了生物活性分子褪黑素,此法可用于测定脑白金胶囊中的褪黑素。     

中子自旋回波：研究蛋白质结构域动力学的利器

蛋白质作为生物系统这种复杂分子机器的重要组成部分之一,理解它们内部的结构及其在不同时间及空间尺度上的运动,对于研究生命的运作机理至关重要。相较于其他实验手段,中子自旋回波技术能探测到更大时空范围的性质,在研究蛋白质内部的结构域动力学方面具有独特的优势。这是一门横跨核物理与核技术、非平衡态统计物理学、分子生物学与蛋白质组学等前沿交叉领域的学科,充满着诸多未知与挑战,也遍布着一探生命奥秘的机遇。文章简述了中子自旋回波实验技术的基本原理和发展历程,阐述其在研究蛋白质结构域动力学方面的方法和技术优势,并介绍了部分实验案例,最后对其应用前景进行探讨与展望。     

Interaction Between 1,2,3-Trichloropropane and Haloalkane Dehalogenase LinB

The haloalkane dehalogenase LinB from Sphingomonas paucimobills UT26 was found to transform the 1,2,3-trichloropropane(TCP) into inorganic halide ions and 2,3-dichloro-1-propanol although the catalytic activity is very low(Kcat=0.005 s-1).In this study,molecular dynamics simulation and docking studies were performed to investigate the binding of TCP to LinB.The docking results indicate that LinB does not restrict TCP to be bound productively in the active site and the water-mediated inhibition occurs in the...     

氧化钛烧结体的氧含量测定

用电子探针X射线微分析(EPMA)方法测定了一系列氧化钛烧结体中的氧含量,并用X射线衍射(XRD)分析对其相态作了研究,所得的结果指出根据产品的氧含量与其某些物理特性之间的内在联系,即可从其表现的某些物理性质估计某一烧结产品的氧化物含量,而所得结果对下一步的镀膜工作具有指导意义.     

Synthesis of 1-aryl-5-methyl-4-substituted-l,2,3-triazoles

As 1-aryl-5-methyl-4-substituted-1,2,3-triazoles often exhibit broad spectrum biological actions, we have synthesized many heterocyclic and condensed heterocyclic compounds which contained 1-aryl-5-methyl-1,2,3-triazol-4-yl functional groups and screened their antibacterical activities^[1,2]. Our further work testified that it was necessary to go on studying such kind of compounds. In order to improve the soluble of these compounds, we chose aniline and p-toluidime as starting materials to synthesize 1-aryl-5-methyl-4-substituted-1,2,3-triazoles 1a-b, 2a-b, 3a-b, 4a-b, 5a, These new compounds all have active reaction groups such as SH, NH₂ as well as OH. So they might react with ω-substituted-ω-bromo-acetophenone and 6a-b, 7a-b, 8a-b, 9a were obtained. They are all soluble in hot alcohol. Under similar conditions it is difficult to let 4a-b react completely with ω-substituted-ω-bromo-acetophenone. We only observed a little new compounds by TLC. By Mannich reaction, 1a-b also could react with formaldelyde and p-toluidime and l0a-b were isolated. The evaluation of the biological activity is in progress.